Automated analyzers have been developed for biochemical analysis of patient samples, such as whole blood, serum, urine, plasma and cerebral spinal fluid. Most such equipment available today is large, complicated to operate, and high in cost.
Operation of existing analyzers is technically complicated. the analyzers typically require specialized operators to be available at all times. They are usually designed for use by large laboratories serving a wide geographic area or by a large medical facility. These existing analyzers carry out tests in an inflexible predefined sequence of operations designed only for efficient, high volume usage.
Such large scale capacity is not always required, particularly in smaller medical clinics where large volumes of blood samples are not tested on a daily basis. The present chemical analyzer was developed to meet the varying practical needs of smaller medical settings. It is designed as a flexible desk-top unit that can be operated by one not having extensive laboratory training. Its throughput is adequate for meeting typical clinical applications. As an example, it can be designed to produce a maximum of 164 test results per hour for routine, single reagent chemistries. Its capacity can be effectively doubled by utilizing two of the chemistry instruments in tandem, both being controlled by a common workstation. To provide a representative wide number of reagents, the analyzer has been designed to have a capacity of 40 reagent containers of two different sizes.
The compact nature of the analyzer can be partially attributed to the fact that a single probe arm and pipette service all of the functional liquid-handling components included within it. The common pipette is used for transferring samples and reagents, as well as for diluting liquids as needed by particular test requirements.
To obtain large volumes of tests, conventional laboratory analyzers are programmed to conduct test procedures in a fixed sequence of events. While the use of predetermined test sequences is practical in high volume chemical analyzer applications, there is a need for more flexible operation when scaling such test procedures to meet the needs of smaller medical facilities.
The present invention provides testing flexibility by permitting random access to each cuvette on a test turntable and to each container (cups, wells and reagent bottles) on a sample/reagent tray. It is therefore not necessary for the instrument to sequence through any predetermined processing steps--the controlling software can tailor the required steps to the tests currently requisitioned. This permits a greater number of tests to be conducted while using a minimum number of containers, cuvettes and reagent bottles. The software controls the sequencing of tests based upon predetermined priority schedules, rather than defined test sequences dictated by the nature of the tests being conducted.
Increased versatility is also provided in the present chemical analyzer by providing the capability of inserting pre-loaded reagents within cuvettes fed to a dispensing magazine that directs them to the turntable. Flexibility is further enhanced by providing random access to a plurality of stacks of incoming cuvettes, some of which can be preloaded and some of which can be empty. This provides the capability of random access to prepackaged chemistry involving powdered or solid reagents to supplement the liquid reagents available on the sample/reagent tray.
Most existing analyzers are limited to accomplishing either photometric tests or potentiometric tests, but not both. The present chemistry analyzer, designed about a photometric testing system, has the capability of servicing a second analytical system, such as a potentiometric system. A single liquid transfer system provides samples to both analytical systems. Their operations are controlled by a common workstation, which also processes all resulting data.
The present chemical analyzer also provides the ability to use two chemical instruments in tandem, both being controlled by a single workstation. Using two chemical instruments increases analyzer dependability by providing redundancy of mechanical components. It also allows one chemical instrument to be dedicated to more specialized analytical applications that might require greater time periods or more fragile reagents. Because the two chemical instruments are controlled by a single workstation to minimize duplication, greater volumes of tests can be conducted at a lower additional capital investment than would be required to purchase a larger test system or a duplicate system.
To meet the intermittent needs of medical offices and clinics, as well as the needs of small or specialized hospitals, serum samples can be introduced to the analyzer one at a time in conventional draw tubes, as well as in batches or single units on sample ring segments that are removable from the sample/reagent tray. The latter method of sample introduction is more likely to be utilized in small or specialized hospital settings where the analyzer is associated with more automated sample handling systems.
Most automated analyzers that accommodate samples provided in conventional draw tubes require that such tubes be delivered into the machine in carrousels or on a dedicated conveyor. The draw tubes are then processed as a group over a significant dwell time within the equipment. One feature desirable in many clinical settings is the ability to aliquot samples from a conventional draw tube without requiring the continued presence of the draw tube during the resulting test sequences. This permits the sample material in the tube to be used simultaneously in other equipment during conduct of complementary test procedures.
A sample tube entry port has been designed to facilitate automatic aliquoting of samples from conventional sealed draw tubes without destroying the seals closing the draw tubes or exposing personnel to accidental contact with the sampled materials. It automatically accommodates draw tubes differing from one another in both tube diameter and length.
The present sample tube entry port has been designed to remove a sample promptly upon receipt of a draw tube. It then immediately releases the draw tube for any other current purposes required in the setting in which the chemical analyzer is used.
The automated controls for the present chemical analyzer minimize the need for extensive operator training. Reagent bottles are automatically read and identified by applied computer coded labels. Sample and reagent sensing that occurs automatically during operation of the analyzer notifies the operator of depleted liquid conditions as they occur.
Disposable cuvettes are provided automatically within the analyzer by a cuvette dispenser. Reloading of the cuvettes into a dispensing magazine included in the chemistry instrument is physically organized to meet the supply needs of the instrument with minimum cuvette handling by the operator.
A reaction turntable is capable of handling a maximum of 48 cuvettes at any given time. Both absorbance and fluorescence polarization tests can be carried out with respect to selected cuvettes through use of a single optical system.
Capacitive sensing of liquid levels is used within the chemistry instrument to maintain updated inventory information. A unique capacitive sensing system is used in conjunction with a probe alignment module to monitor both radial and axial positioning of the pipette. These procedures detect bent conditions of the pipette prior to damage of associated equipment.
Further details concerning the system will be evident from the following description.